Cml\Cache\Redis::hash PHP Method

    private function hash($key)
    {
        $serverNum = count($this->conf['server']);
        $success = sprintf('%u', crc32($key)) % $serverNum;
        if (!isset($this->redis[$success]) || !is_object($this->redis[$success])) {
            $instance = new \Redis();
            $connectToRedisFunction = function ($host, $port, $isPersistentConnect) use($instance) {
                if ($isPersistentConnect) {
                    return $instance->pconnect($host, $port, 1.5);
                } else {
                    return $instance->connect($host, $port, 1.5);
                }
            };
            $isPersistentConnect = !(isset($this->conf['server'][$success]['pconnect']) && $this->conf['server'][$success]['pconnect'] === false);
            $connectResult = $connectToRedisFunction($this->conf['server'][$success]['host'], $this->conf['server'][$success]['port'], $isPersistentConnect);
            $failOver = null;
            if (!$connectResult && !empty($this->conf['back'])) {
                $failOver = $this->conf['back'];
                $isPersistentConnect = !(isset($failOver['pconnect']) && $failOver['pconnect'] === false);
                $connectResult = $connectToRedisFunction($failOver['host'], $failOver['port'], $isPersistentConnect);
            }
            if (!$connectResult && $serverNum > 1) {
                $failOver = $success + 1;
                $failOver >= $serverNum && ($failOver = $success - 1);
                $failOver = $this->conf['server'][$failOver];
                $isPersistentConnect = !(isset($failOver['pconnect']) && $failOver['pconnect'] === false);
                $connectResult = $connectToRedisFunction($failOver['host'], $failOver['port'], $isPersistentConnect);
            }
            if (!$connectResult) {
                Plugin::hook('cml.cache_server_down', [$this->conf['server'][$success]]);
                throw new CacheConnectFailException(Lang::get('_CACHE_CONNECT_FAIL_', 'Redis', $this->conf['server'][$success]['host'] . ':' . $this->conf['server'][$success]['port']));
            }
            $password = false;
            if (is_null($failOver)) {
                if (isset($this->conf['server'][$success]['password']) && !empty($this->conf['server'][$success]['password'])) {
                    $password = $this->conf['server'][$success]['password'];
                }
                isset($this->conf['server'][$success]['db']) && $instance->select($this->conf['server'][$success]['db']);
            } else {
                if (isset($failOver['password']) && !empty($failOver['password'])) {
                    $password = $failOver['password'];
                }
                isset($failOver['db']) && $instance->select($failOver['db']);
                Log::emergency('redis server down', ['downServer' => $this->conf['server'][$success], 'failOverTo' => $failOver]);
                Plugin::hook('cml.redis_server_down_fail_over', ['downServer' => $this->conf['server'][$success], 'failOverTo' => $failOver]);
            }
            if ($password && !$instance->auth($password)) {
                throw new \RuntimeException('redis password error!');
            }
            $instance->setOption(\Redis::OPT_PREFIX, $this->conf['prefix']);
            $this->redis[$success] = $instance;
        }
        return $this->redis[$success];
    }